Cutting tool and system for coring a bowl using a lathe

ABSTRACT

A cutting tool piece is provided including a rear portion and a lead portion, the lead portion including a front section having an upper side angled downwardly and forwardly and a lower side angled upwardly and forwardly to form a transverse lead cutting edge. The rear portion includes a hole to secure the tool piece to a cutting tool and transverse cutting edges extending outwardly from side walls of the front section. A system is also described for cutting a bowl by coring out an interior portion of a wood block by applying the cutting tool which is curved and rotatably mounted to a post. Its lead end with the tool piece attached creates a circular groove. The cutting tool is advanced on a path which curves toward the central axis of the lathe.

This invention relates to a cutting piece, a cutting tool, a system forforming a bowl utilizing a lathe, and a method for using theaforementioned system.

Lathes are used in the art of carving wood pieces by spinning woodpieces at sufficient speed and applying a sharp instrument to the woodpiece for patterning or carving. The lathe typically includes a flathorizontal bed with rails mounted on the bed. Typically a support blockor tool rest for supporting a cutting tool is slidably mounted on thebed rails. The cutting tool may be manually applied to the face of awood block, using the support block or tool rest as a fulcrum tomanipulate the tool upon the wood. When cutting tools are manuallyapplied, accurate, consistent patterning of the wood piece is difficultto achieve. Cutting tools have also been secured upon the lead edge of acutting member which is slidably or rotatably secured to the supportblock or tool rest. Sliding the support block along the bed rails to aposition adjacent to the wood piece allows for selective application ofthe cutting piece by rotating or sliding the cutting member upon thesliding block.

The use of a lathe machine to construct bowls is known. A bowl may beconstructed using a lathe by manually applying a cutting instrument tocarve out an interior portion of the wood piece. Typically the cuttinginstrument is rested on a tool rest or support block and the tool restor support block acts as a fulcrum for the tool. Manual application ofthe tool makes it difficult to achieve consistency between work pieces.To allow for more consistent application when constructing a bowl usinga lathe machine, a cutting tool may be rotatably mounted via a post upona support block slidable on the bed rails. The support block is slidablypositioned and secured adjacent to the wood piece. A cutting memberhaving a cutting piece at its lead end extends from the post. Thecutting member may then be rotated on a fixed path into contact with thewood piece creating a fixed radius cored bowl. To bore out bowls ofselectively various sizes, the cutting members have consisted of aseries of blades of varying curves and lengths. Using such fixed pathcutting machines makes the desired consistency between bowls easier toachieve.

Known cutting pieces secured at the lead ends of cutting members used tocut wood using a lathe have been known to be susceptible to catching inthe wood, causing excess vibration and excessive rotational forcescaused by the spinning wood piece. These factors in turn tend to causeexcess wear on the lathe machine and damage and distortion of thecutting member, posts and various components of the lathe machine.

Cutting pieces are known to have a substantially flat or rounded upperside extending from the lead edge of a cutting member to a cutting edgeextending substantially transversely across the lead edge of the piece.Typically, a substantially vertical and/or slightly angled lead faceextends downwardly from the transverse cutting edge. The transversecutting edge is applied to the wood block attached to the lathe. Suchpieces are susceptible to catching and tend to create significantrotational force on the cutting edge as it is applied to the rotatingwood block.

Cutting pieces are also disclosed having a spear cutting point forapplication to the wood block. Although such a spear point will reducethe likelihood of catching, they are known to cause significantvibration to the machine.

Tool pitch is the rotational pulling force on the cutting edge of thetool caused as it is applied to the rotating block of wood. As thecutting edge extends into the wood and away from the support block ortool support, tool pitching increases.

In order to reduce the amount of pitch on the lead edge of the cuttingmember, various types of supports are known to be positionable below thelead edge of the cutting tool as it is applied to the wood block. Such asupport surface supports the cutting member as it is initially insertedinto the wood. Because the support sits directly below or close to thelead edge of the cutting member, lead edge pitching is reduced.

Once the lead edge of cutting tool has been inserted substantially intothe wood block, it becomes more susceptible to pitching because there isno support directly below it. As the lead edge of the cutting memberenters the wood piece when cutting a groove, supports disclosed in theprior art are not capable of following the lead edge of the cutting toolinto the wood. Thus, such supports are not capable of preventingpitching as the tool head is advanced into the block of wood. Theproblem of pitching of the lead edge of the cutting tool becomes greaterwhen using longer cutting members curved for bowls of larger radius,since they are separated by more distance from the tool support as theyenter into the wood piece.

There is a need for an improved cutting piece or attachment for cuttingwood using a lathe and there is a need for an improved system forforming or coring bowls using a lathe.

The present invention provides an improved cutting piece for use with acutting tool that can be used to form a bowl by means of a lathe. Thecutting tool attachment disclosed herein reduces the catching of thetool head when cutting into a block of wood.

According to another aspect of this invention, there is also provided animproved bowl forming system which can be used with a lathe and whichprovides support to the lead edge of a cutting tool as it advances intothe wood piece thereby reducing tool pitch and subsequent stress on thelathe and components.

In accordance with a first aspect of the invention there is provided acutting piece for securement to a lead end of a cutting tool comprisinga rear portion securable to the lead end of the cutting tool by asecuring mechanism formed on the rear portion. A lead portion of thecutting piece extends forwardly from the rear portion and the leadportion having a front section is adapted to extend beyond the lead endof the cutting tool. The lead portion is narrower in a transversedirection than a forward end of the rear portion and it has twosidewalls located on opposite sides thereof. The front section has anupper side angled downwardly and forwardly and a lower side angledupwardly and forwardly. The upper and lower sides form a front end ofthe lead portion which forms a leading cutting edge. The rear portionincludes further cutting edges extending outwardly from a respective oneof the side walls of the lead portion.

According to second aspect of the invention, there is provided a systemfor forming a bowl utilizing a lathe which rotates a block for the bowlabout a horizontal axis during use of the system. The system comprises asupport block slidably engageable on the lathe bed and positionableadjacent a face of the wood block when the block is mounted for rotationon the lathe. A first post is mounted on the support block and extendsupwardly therefrom. An elongate cutting tool is rotatably mounted on thefirst post, this cutting tool including a cutting portion which iscurved and extends to a lead end. The lead end includes a cutting devicefor cutting and coring the block and applicable to the face of the blockby rotating the cutting tool about the first post so that the cuttingdevice cuts a circular groove in the block about the rotation axis. Thecutting portion extends on a curved path toward this axis as the leadend advances into the block. A second post includes an upper supportsurface. A support member is rotatably secured on this post and ismovable thereupon from a first support position to a secondary supportposition. In the first support position, the second post is positionedadjacent the face of the block. In the secondary support position, thesupport member is arranged such that it can be advanced into the groovedirectly below the cutting tool, thereby providing support for the leadend of the cutting portion as the cutting portion is advanced throughthe block.

According to a third aspect of the invention, there is provided acutting tool for use with a lathe, the tool comprising an elongate bodyportion which is curved in the lengthwise direction thereof, has twolateral sides located on opposite sides of the body portion, and has alead end with a lead portion projecting forwardly beyond the two lateralsides. The lead portion has a front section having an upper side angleddownwardly and forwardly and a lower side angled upwardly and forwardlysuch that the upper and lower sides form a leading cutting edge. Thelead portion also has two vertically extending side walls located onopposite sides thereof. The lead end of the tool is formed with outercutting edges extending transversely of the lateral sides and outwardlyfrom a respective one of the vertically extending sidewalls of the leadportion.

An advantage provided by the first and third aspect of the invention isthat the configuration of the cutting piece reduces the likelihood ofcatching of the cutting piece and cutting tool as they are applied tothe block for cutting a groove.

An advantage to the second aspect of the invention is that support canbe provided to the lead edge of the cutting tool as it advances into agroove created in the block, therefor reducing the amount of tool pitchand stress and reducing vibration and wear and stress on the lathemachine and components thereof.

According to a further aspect of the invention, there is provided acutting piece for cutting a groove in a workpiece mounted in a lathe,the cutting piece comprising a rear portion securable to a lead end ofthe cutting tool and a lead portion rigidly connected to the rearportion and extending forwardly from the rear portion. The lead portionis narrower in a transverse direction than an adjacent forward end ofthe rear portion, is adapted to extend beyond the lead end of thecutting tool, and has two sidewalls located on opposite sides of thelead portion and a sloping upper side that extends downwardly andforwardly and a lower side sloping upwardly and forwardly such that theupper and lower sides form a leading cutting edge. The upper and lowersides define an angle not exceeding ninety degrees. The rear portion hasfurther cutting edges each extending outwardly from a respective one ofthe sidewalls of the lead portion.

Preferred embodiments of the invention will now be described inconjunction with the accompanying drawings.

In the drawings,

FIG. 1 is perspective view of the preferred embodiment of the cuttingpiece;

FIG. 2 is front elevation of the preferred embodiment of the cuttingpiece;

FIG. 3 is a rear side elevation of the preferred embodiment of thecutting piece;

FIG. 4 is a side elevation of the preferred embodiment of the cuttingpiece;

FIG. 5 is a top view of the preferred embodiment of the cutting piece;

FIG. 6 is a perspective view of the preferred embodiment of the cuttingpiece attached to a preferred cutting tool;

FIG. 7 is a perspective view of a preferred embodiment of the cuttingsystem in a first position;

FIG. 8 is another perspective view of the preferred embodiment of thecutting system in this first position;

FIG. 9 is a perspective view of the preferred embodiment of the cuttingsystem in a second position;

FIG. 10 is another perspective view of the preferred embodiment of thecutting system in the second position;

FIG. 11 is a further perspective view of the preferred embodiment of thecutting system in the first position which is also shown in FIGS. 7 and8;

FIG. 12 is a side view of an alternate form of curved holder for thecutting piece of the invention; and

FIG. 13 is a top view of the curved holder of FIG. 12.

Shown in FIGS. 1 to 6 is one preferred embodiment of the cutting pieceor attachment for cutting a groove in a workpiece such as a wood block.The preferred embodiment of the cutting piece 10 has a rear portion 12securable to a lead end of a cutting tool and a lead portion 14 whichextends forwardly from the rear portion. The lead portion has a frontsection 16 extending beyond the lead end 74 of a cutting tool 70. Thefront section has a sloping upper side 24 angled downwardly andforwardly, and a lower side 26 angled upwardly and forwardly. The upperside 24 and lower side 26 meet at a front end 28 of the lead portion toform a leading transverse cutting edge 30. Preferably the upper side 24and the lower side 26 define an angle not exceeding 90 degrees and morepreferably an angle less than 90 degrees. In one preferred embodiment,the acute angle defined between the upper side 24 and the lower side isabout 75 degrees and the preferred range for this angle is between 60and 75 degrees. The edge 30 extends substantially transversely relativeto a central longitudinal axis A extending from a rear end 31 of thecutting piece to the leading cutting edge.

Preferably the cutting piece 10 is securable to the upper surface of thelead end 74 of the cutting tool 70 by means of a screw 32 (see FIG. 6)inserted through a bore 34 in the rear portion of the cutting piece 10and fastened to the lead end of the cutting tool. Alternatively it ispossible to omit the bore 34 and to attach the cutting piece by othermeans such as brazing.

Although the preferred edge 30 extends transversely as shown, it ispossible for this edge to extend at a small acute angle, for example upto about 10 degrees, from the perpendicular to the central, longitudinalaxis A.

Preferably, the rear portion 12 has cutting edges 36 and 38 which eachextend beyond the side walls 40, 42 of the cutting tool. The cuttingedges also extend outwardly from a respective one of two oppositesidewalls 41,43 of the lead portion, which is narrower in a transversedirection than a forward end of the rear portion 12. The cutting edges36, 38, extend beyond the side walls 40, 42 so as to create an effectivecutting width for the groove which is greater than the width of thecutting tool. As shown in FIGS. 6 to 10, application of the cuttingpiece 10, secured to the lead end 74 of the cutting tool 70, to a woodblock 100 rotating on a lathe 102, creates a circular groove 104 in saidwood 100 which has a width greater than the width of the cutting tool,thereby allowing the cutting tool to be advanced into the groove 104. Itshould be noted that the spear point formed by the upper and lower sides24, 26 acts as an effective brake to prevent the positive cutting edges36, 38 from being pulled into the wood block as the cutting proceeds.

Preferably the cutting piece 10 is made of a suitable steel and includesa plurality of longitudinal slots 48 on its bottom side, which areconfigured to align with mating ridges on an upper portion of the leadend of the cutting tool 70 to help locate the cutting piece 10 on thecutting tool and to enhance rigid securement of the cutting piece on thecutting tool. Instead of steel, the cutting piece can be made of otherknown hard cutting materials such as carbide.

Shown in FIGS. 7 to 11 is the preferred embodiment of a system forforming or coring a wooden bowl utilizing a lathe. The preferredembodiment includes a support block 60, slidably engageable on supportrails 62 of a lathe bed 64. The support block is releasably positionableadjacent a face of a wood block 100 which is rotatable about ahorizontal axis on the lathe 102. The support block preferably includesan elongate slot 61 on its upper surface, this slot extendingtransversely of the support rails 62 of the lathe. Preferably a firstpost 66 is mounted on the support block by bolts 68 extending throughtwo holes formed in a connecting plate at the base of the post. Thecutting tool 70 is rotatably mounted on the first post. The cutting toolincludes a cutting portion 72 which is curved and extends to the leadend 74. The lead end 74 has the cutting piece 10 extending therefrom.The cutting piece at the lead end is applicable to the face 101 of saidwood block 100 by rotating the cutting tool about the first post.Preferably, the cutting tool also includes a handle portion 76 extendinghorizontally from the rear end of cutting portion. The handle portioncan be utilized to rotate the lead end of the cutting portion intoengagement with the face of the wood block. As the wood block spins onthe lathe about the horizontal lathe axis, and the lead end withattached cutting piece is applied to the wood block face 101 so as tocut thereinto, a circular groove 104 in the wood block is created whichextends around the lathe axis. Further rotation of the cutting toolabout the first post 66 causes the lead edge of the cutting portion toextend into the wood block on a curved path. As the lead edge advancesinto the wood block, its moves closer to the axis of rotation of thewood block. As such, the diameter of the circular groove 104 diminishesas the lead edge advances into the wood block. Once the lead edgeadvances into the wood and approaches the axis of rotation of the woodblock, the lead edge causes a central portion of wood 108 to becomeseparable from the wood block. A bowl or concave cavity is formed by theremoved central wood portion 108.

The preferred system further includes a support post 80 (hereinaftersometimes referred to as the “second post”) providing an upper supportsurface 82 and a support member 84 rotatable about the post 80 andextending from this post in a curved path which is similar in itscurvature to that of the cutting portion 72. The support post isreleasably slidable upon the upper side of the support block and isreleasably held in the desired position by means of a bolt 92 insertedthrough a slot 86 in a base plate 90 of the post. The bolt 92 extendsthrough the groove 61 in the support block and is held in the block. Thesupport post is movable from a first initial position shown in FIGS. 7,8 and 11 to a second position shown in FIGS. 9 and 10.

In the first position, the support post 80 sits adjacent to the woodblock face and the lead edge of the cutting portion rests on the supportsurface. In the first support position the support surface 82 sitsadjacent the wood face and is positioned below the location where thecutting member engages the wood block thereby providing support for thelead edge 74 of the cutting tool as it engages the wood face. In thefirst position, the supporting member 84 is rotated out of contact withthe wood block. As the lead edge 74 is advanced into the wood block, thesupport post 80 can be moved into the second position. Preferably thesupport post is moved into the second position as follows: The bolt 92is slightly loosened so as to allow the support post to move along thegroove 61 in the support block and to allow rotation and sliding of thepost about the bolt 92. In the second support position, the support postis rotated and aligned such that the support member 84 can be advancedinto the groove at a position directly below the cutting portion 72.Once the second post is located in the second position, the supportmember 84 may be advanced by advancing the support post towards the woodblock. The support post can be selectively secured and released inprogressively advanced positions by tightening and loosening the bolt92. Thus, the support member provides support for the lead edge 74 ofthe cutting tool as it is advanced into the groove. By keeping thesupport member close to the lead edge of the cutting portion, tool pitchis diminished as the cutting portion extends into the wood block.

The system described above is preferably used as follows: The user fixesand rotates a wood block 100 upon a lathe, rotating it about a centralhorizontal axis. The support block 60 is positioned adjacent to the woodblock. The cutting tool is rotated about the first post 66 by the handleportion 76 and the lead edge 74 is applied to the wood face, therebycreating the circular groove 104. The support surface 82 is positioneddirectly below the lead edge as it engages the wood face therebyproviding support therefor.

As the groove 104 becomes deeper, the support post 80 is moved to thesecondary support position. The cutting portion 72 is advanced furtherinto the wood block. The support member 84 is inserted into the grooveat a position below the cutting member and is advanced into the grooveproviding support for the lead edge of the cutting member as it advancesinto the groove, reducing tool pitch. The cutting tool 72 continues tobe advanced into the groove, with the support member 84 providingsupport therefor until an internal portion of the wood block isseparated from the wood block, thereby leaving a bowl or concave cavityin the wood block.

The preferred features of the preferred cutting piece 10 will now bedescribed with reference again to FIGS. 1 to 5 of the drawings. Withrespect to the rear portion of this cutting piece, the preferredembodiment has two vertically extending sidewalls 120 and 122. It willbe seen that these sidewalls taper slightly towards the centrallongitudinal axis A in a rearwards direction. At the front end of thesesidewalls are two vertically extending leading faces 124 and 126. Asillustrated in FIG. 5, where the sidewalls meet the leading faces, thecorner edges are preferably rounded or formed with a small radiusindicated at 128. These radii have not been shown in some of the figuresfor ease of illustration. The end piece has a bottom 130 which for thepurposes of this description can be considered as extending horizontally(not including the aforementioned grooves 48 formed in the bottom). Ascan be seen from FIG. 4, the preferred leading faces 124, 126 extend atan obtuse angle that is more than 90 degrees to the bottom 130. In apreferred embodiment, this obtuse angle ranges from about 95 degrees to100 degrees and is indicated by angle X. The end piece also has a top132 which is planar and which can extend at a relatively small acuteangle to the plane of the bottom 130. Thus, when the bottom 130 is in ahorizontal plane, the plane of the top 132 extends at a small acuteangle to the horizontal plane and slopes upwardly and forwardly. Inother words, the top 132 extends at a positive rake. In the illustratedembodiment, this small acute angle or positive rake is between 5 and 10degrees (most preferably 5 degrees). In this preferred embodiment, theacute angle formed between the two leading faces 124, 126 and the top ofthe end piece and indicated at Y in FIG. 4 is approximately 80 degrees.Because of the slight upward and forward slope of the top, it will beseen that the two cutting edges 36, 38 formed on opposite sides of theend piece have a positive edge geometry which is good for the freecutting of the wood. This is different than the negative geometry formedby the spear point created by the aforementioned upper side 24 and thelower side 26. The advantage of the negative geometry of the spear pointformed by the lead portion 14 is that it is non-catching when applied tothe rotating wood block.

In an alternate form of the cutting piece 10, the top 132 is parallel tothe plane of the bottom 130 and this cutting piece is then mounted on acutting tool holder such as that shown in FIGS. 12 and 13 so that itstop 132 will extend in use at a small angle to the horizontal plane,i.e. five degrees.

It will be seen from the above description of FIGS. 7 to 11 that thecutting tool 70 has a vertical pivot axis formed by its support post. Itcan be moved in two horizontal directions during use of the cuttingtool. Thus the post 66 can be moved horizontally along the support rails62 by adjusting the position of the support block 60 and it can also bemoved transversely of the support rails 62 by adjusting the position ofthe post along the slot 61 (using the aforementioned adjustment bolt68). By being able to move the support post 66 in these two differenthorizontal directions, the centre point of the radius of the cuttingportion 72 can be moved. This advantage together with the provision ofcutting portions 72 of cutting tools having different radii provides thepossibility of producing a wide variety of bowl sizes using the systemof the invention.

Another preferred feature of the present system is the manner in whichthe cutting tool 70 is mounted on the post 66. As shown in FIGS. 7 and9, for example, there is a short upward vertical extension of the postat 140. Mounted on the top of this extension is a bent bar 142 which hasa horizontally extending section 144 and then a Z-shaped section 146 towhich the aforementioned handle 76 is connected. It will be particularlynoted that the top of the horizontally extending section 144 ispositioned below the axis for rotation of the lathe. It will beunderstood that this axis for rotation is located approximately in thecenter of the wood block from which the bowl is being formed. Theadvantage of supporting a cutting tool in this manner is that thisarrangement enables the standard tail stock (not shown) of the lathe tobe used, if required to support the wood block as it is being rotated.In other words the tail stock can be engaged with the centre of the faceof the wood block 100 in which the groove 104 is being formed. Thus atvarious times during the use of the system of the invention, the tailstock of the lathe can be used to prevent excess vibration which couldotherwise be a problem, particularly on a weaker lathe machine.

FIGS. 12 and 13 illustrate an alternate configuration for the curvedtool holder that holds and support the cutting piece 10. This alternatecurved tool holder 150 can be used in place of the cutting portion 72shown in FIGS. 6 to 11 of the drawings. As with the version shown inFIGS. 6 to 11 this tool holder extends through a circular arc from arear end 152 to its lead end 154. In one particular embodiment this archas a radius of 6.81 inches but the radius can clearly vary dependingupon the particular coring requirements. The holder can be made from astrip of steel which has a width in one particular embodiment of 1.50inches. The holder 150 has a relatively narrow or short front endsection 156 on which the cutting piece 10 can be mounted. There is asloping section at 158 where the top edge 160 of the holder slopes downto the front end section 156. In the illustrated embodiment, the angle Zof the slope is about 30 degrees. Also in a preferred embodiment thethickness of the steel strip forming the holder is 0.25 inch. A threadedbore 162 is formed in the front end section 156 and, as indicated, thisbore is sized to receive a screw used to hold the cutting piece.

It will be particularly noted that the top edge at 164 of the front endsection extends at a small angle to the horizontal and at the same smallangle to the main portion of the top edge on the rear section of theholder. In one preferred embodiment, this small angle is 5 degrees withthe top edge section 164 sloping downwardly and rearwardly. Theadvantage of this configuration is that the cutting piece 10 can then bemade with parallel top and bottom surfaces. By mounting the cuttingpiece on a slightly sloping surface, the top 132 of the cutting piecewill then be sloped at a small acute angle downwardly and rearwardly inthe preferred manner.

It has been found that with the use of the cutting piece and cuttingtool of the invention and with the use of the above described system forforming a bowl, a wood bowl can be produced which has a good finish withthe wood fibres cleanly severed. In addition with the use of the cuttingdevices in the aforementioned system, a user generally has no difficultycoring the wood block to where the wood core will break out with only aslight tap or will simply fall out, a result which is generally notobtained with other known methods.

Since various modifications can be made in the invention as hereinabovedescribed, and many different embodiments of same can be made within thespirit and scope of the invention, it is intended that all mattercontained in the above specification shall be interpreted asillustrative only and not in a limiting sense. All variations andmodifications of this invention as fall within the scope of theaccompanying claims are intended to be part of this invention.

1. A cutting piece for securement to a lead end of a cutting toolcomprising: a rear portion securable to said lead end of said cuttingtool by securing means formed on said rear portion, and a lead portionextending forwardly from said rear portion, said lead portion beingnarrower in a transverse direction than a forward end of said rearportion, having a front section adapted to extend beyond the lead end ofsaid cutting tool, and having two sidewalls located on opposite sides ofsaid lead portion, said front section having an upper side angleddownwardly and forwardly and a lower side angled upwardly and forwardlysuch that said upper and lower sides form a front end of said leadportion and said front end forms a leading cutting edge; wherein saidrear portion includes further cutting edges each extending outwardlyfrom a respective one of said sidewalls of said lead portion.
 2. Acutting piece according to claim 1 wherein said cutting piece is made ofsteel and wherein said upper side and said lower side define an anglenot exceeding 90 degrees.
 3. A cutting piece according to claim 1wherein said securing means is a bore formed in the rear portion andadapted to receive a screw for attachment of said cutting piece to saidlead end of said cutting tool.
 4. A cutting piece according to claim 1wherein said rear portion includes a bottom side having a plurality ofhorizontal grooves which are releasably engageable with mating ridges onan upper side of said lead end of said cutting tool.
 5. A cutting pieceaccording to claim 1 wherein said rear portion has an upper side andleading, vertically extending faces from which said lead portion extendsand said further cutting edges are formed where said verticallyextending faces meet said upper side.
 6. A cutting tool for use with alathe, said cutting tool having a lead end and first and secondsidewalls and a cutting piece formed on said lead end and comprising arear portion and a lead portion extending forwardly from said rearportion, said lead portion being narrower in a transverse direction thana forward end of said rear portion and having two sidewalls located onopposite sides of said lead portion, said lead portion having an upperside angled downwardly and forwardly and a lower side angled upwardlyand forwardly such that said upper and lower sides form a front end ofsaid lead portion and said front end forms a leading cutting edge,wherein said rear portion includes further cutting edges each extendingoutwardly from a respective one of said sidewalls of said lead portion.7. Use of the cutting piece according to claim 1 secured to said leadend, to cut a block rotating on a lathe, whereby said cutting piececreates a groove in said block of greater width that the width of saidcutting tool thereby allowing said cutting tool to be advanced into saidgroove.
 8. A cutting tool for use with a lathe, said tool including anelongate body portion which is curved in the lengthwise directionthereof, has two lateral sides located on opposite sides of said bodyportion, and has a lead end with a lead portion projecting forwardlybeyond said two lateral sides, said lead portion including a frontsection having an upper side angled downwardly and forwardly and a lowerside engled upwardly and forwardly such that said upper and lower sidesform a leading cutting edge, said lead portion also having twovertically extending sidewalls located on opposite sides thereof,wherein said lead end is formed with outer cutting edges extendingtransversely of said lateral sides and outwardly from a respective oneof said vertically extending sidewalls of said lead portion.
 9. Acutting tool according to claim 8 wherein a separable cutting pieceforms said lead portion and said outer cutting edges and said elongatebody portion includes a curved, elongate holder for said cutting piece,said cutting piece being attached to said elongate holder by a threadedfastener.
 10. A cutting tool according to claim 9 wherein said cuttingpiece includes a rear portion having a bore extending therethrough andsaid threaded fastener extends through said bore in order to attach saidcutting piece to said curved, elongate holder.
 11. A cutting toolaccording to claim 8 wherein said upper side and said lower side definean acute angle that is less than 90 degrees.
 12. A cutting piece forcutting a groove in a workpiece mounted in a lathe, said cutting piececomprising a rear portion securable to a lead end of a cutting tool anda lead portion rigidly connected to said rear portion and extendingforwardly from said rear portion, said lead portion being narrower in atransverse direction than an adjacent forward end of said rear portion,being adapted to extend beyond said lead end of the cutting tool, andhaving two sidewalls located on opposite sides of said lead portion anda sloping upper side that extends downwardly and forwardly and a lowerside sloping upwardly and forwardly such that said upper and lower sidesform a leading cutting edge, wherein said upper and lower sides definean angle not exceeding ninety degrees and said rear portion has furthercutting edges each extending outwardly from a respective one of saidsidewalls of said lead portion.
 13. A cutting piece according to claim12 wherein said leading cutting edge extends substantially transverselyto a central longitudinal axis of the cutting piece.
 14. A cutting pieceaccording to claim 12 wherein said rear portion has a top surface andleading faces from which said lead portion extends, said further cuttingedges being formed where said leading faces meet said top surface.
 15. Acutting piece according to claim 14 wherein said top surface of the rearportion slopes upwardly in a forwards direction towards said leadportion when said cutting piece is secured to said lead end of saidcutting tool.
 16. A cutting piece according to claim 12 wherein saidrear portion includes a bottom side having a plurality of horizontalgrooves which are releasably engageable with mating ridges on an upperside of said lead end of said cutting tool.
 17. A cutting pieceaccording to claim 12 wherein said rear portion has a verticallyextending bore extending therethrough, said bore being provided for ascrew that can be used to secure said cutting piece to said cuttingtool.
 18. A cutting piece according to claim 12 wherein said upper andlower sides define an acute angle of approximately 75 degrees.